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Extremophil bacteria at high oceanic depth

Pyrococcus abyssi are chemosynthetic bacteria. They live in extreme conditions (black smokers of oceanic ridges) : their energy source comes from the hydrogen oxydation.




At the level of the oceanic ridges, zone where the oceanic crust is formed with a divergence movement, the black smokers release water that is heated by the magma. Around these hydrothermal sources, many living beings have been identified (mussels, prawns, etc...). All this biodiversity comes from a variety of bacteria, that could be at the origin of life in the marine environment. These Pyrococcus abyssi are said to be autotrophic because they produce their organic molecules without consuming the ones of other living-beings. As the environment is poor in light, they don't use light as a source of energy.



What is the energy source that is used ? Scientists of the "CNRS" have observed that the Pyrococcus abyssi were able to consume half of hydrogen dissolved in the thermal water. Moreover, the gene hupL, responsible for the hydrogen's oxydation, has been discovered in the genotype of these bacteria. The use of hydrogen is therefore an important factor for these thermophile living beings. Until now, that's the oxydation of methane and sulphides that was identified as the principal energy source. However, hydrogen's oxydation is more profitable : it produces seven times more energy than methane's oxydation and eighteen times more than sulfide's oxydation. This metabolism is called chemosynthesis.



Photography : Pyrococcus abyssi : from

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